<?php

namespace App\Libs\Ethtool;

use Elliptic\EC;
use kornrunner\Keccak;

define("AddressPrefix", "19");
define("NormalType", '57');
define("ContractType", '58');
define("AddressStringLength", 35);
define("AddressLength", 26);
define("KeyCurrentVersion", 4);
define("KeyVersion3", 3);

class KeyStore
{
    static function save($privateKey, $password, $dir)
    {
        $address = self::privateToAddress($privateKey);
        $opts = [];
        try {
            $salt = isset($opts['salt']) ? $opts['salt'] : random_bytes(32);
            $iv = isset($opts['iv']) ? $opts['iv'] : random_bytes(16);
        } catch (\Exception $e) {
            throw $e;
        }
        $kdf = isset($opts['kdf']) ? $opts['kdf'] : "scrypt";
        $kdfparams = array(
            "dklen" => isset($opts['dklen']) ? $opts['dklen'] : 32,
            'salt' => bin2hex($salt),
        );
        if ($kdf === 'pbkdf2') {
            $kdfparams['c'] = isset($opts['c']) ? $opts['c'] : 262144;
            $kdfparams['prf'] = 'hmac-sha256';
            $derivedKey = hash_pbkdf2("sha256", $password, $salt, $kdfparams['c'], $kdfparams['dklen'] * 2, false);
        } else if ($kdf = 'scrypt') {
            $kdfparams['n'] = isset($opts['n']) ? $opts['n'] : 4096;
            $kdfparams['r'] = isset($opts['r']) ? $opts['r'] : 8;
            $kdfparams['p'] = isset($opts['p']) ? $opts['p'] : 1;
            $derivedKey = self::getScrypt($password, $salt, $kdfparams['n'], $kdfparams['r'], $kdfparams['p'], $kdfparams['dklen']);
        } else {
            throw new \Exception('Unsupported kdf');
        }
        $derivedKeyBin = hex2bin($derivedKey); //$derivedKey is a hex string
        $method = 'aes-128-ctr';
        $ciphertext = openssl_encrypt(hex2bin($privateKey), $method, substr($derivedKeyBin, 0, 16), $options = 1, $iv); //binary strinig
        $mac = hash("sha3-256", substr($derivedKeyBin, 16, 32) . $ciphertext . $iv . $method);
        try {
            $uuid = self::guidv4(random_bytes(16));
        } catch (\Exception $e) {
            throw $e;
        }
        $json = array(
            "version" => KeyCurrentVersion,
            "id" => $uuid,
            "address" => $address,
            'crypto' => array(
                'ciphertext' => bin2hex($ciphertext),
                'cipherparams' => array(
                    'iv' => bin2hex($iv),
                ),
                'cipher' => $method,
                'kdf' => $kdf,
                'kdfparams' => $kdfparams,
                'mac' => $mac,
                'machash' => 'sha3256'
            ),
        );

        $txt = json_encode($json);
        $wallet = $dir . '/' . substr($address, 2) . '.json';
        file_put_contents($wallet, $txt);
        return $wallet;
    }


    static function load($password, $wallet)
    {
        $input = file_get_contents($wallet);

        $json = json_decode($input);
        if ($json->version !== KeyVersion3 && $json->version !== KeyCurrentVersion)
            throw new \Exception('Not supported wallet version');
        if ($json->crypto->kdf === 'scrypt') {
            $kdfparams = $json->crypto->kdfparams;
            $derivedKey = self::getScrypt($password, hex2bin($kdfparams->salt), $kdfparams->n, $kdfparams->r, $kdfparams->p, $kdfparams->dklen); //hex string
        } else if ($json->crypto->kdf === 'pbkdf2') {
            $kdfparams = $json->crypto->kdfparams;
            $derivedKey = hash_pbkdf2("sha256", $password, hex2bin($kdfparams->salt), $kdfparams->c, $kdfparams->dklen * 2, false);
        } else {
            throw new \Exception('Unsupported key derivation scheme');
        }
        $derivedKeyBin = hex2bin($derivedKey);
        $ciphertext = hex2bin($json->crypto->ciphertext);
        $method = $json->crypto->cipher;
        $iv = hex2bin($json->crypto->cipherparams->iv);
        if ($json->version === KeyCurrentVersion) {
            $mac = hash('sha3-256', substr($derivedKeyBin, 16, 32) . $ciphertext . $iv . $method);
        } else {
            $mac = hash('sha3-256', substr($derivedKeyBin, 16, 32) . $ciphertext);
        }
        if ($mac !== $json->crypto->mac) {
            throw new \Exception('Key derivation failed - possibly wrong passphrase');
        }
        $seed = openssl_decrypt($ciphertext, $method, substr($derivedKeyBin, 0, 16), $options = 1, $iv);
        if (strlen($seed) < 32) {
            $string = hex2bin("00000000" . "00000000" . "00000000" . "00000000" . "00000000" . "00000000" . "00000000" . "00000000") . $seed;
            $seed = substr($string, -32);
        }
        //echo "seed: ", bin2hex($seed) ,PHP_EOL;
        //$this->setPrivateKey(bin2hex($seed));
        return bin2hex($seed);
    }

    static function privateToAddress($priv_hex)
    {
        $ec = new EC('secp256k1');
        $keyPair = $ec->keyFromPrivate($priv_hex);
        $public = $keyPair->getPublic()->encode('hex');
        return "0x" . substr(Keccak::hash(substr(hex2bin($public), 1), 256), 24);
    }

    static function guidv4($data)
    {
        assert(strlen($data) == 16);
        $data[6] = chr(ord($data[6]) & 0x0f | 0x40); // set version to 0100
        $data[8] = chr(ord($data[8]) & 0x3f | 0x80); // set bits 6-7 to 10
        return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
    }

    static function getScrypt($password, $salt, $N, $r, $p, $kdlen)
    {
        if ($N == 0 || ($N & ($N - 1)) != 0) {
            throw new \InvalidArgumentException("N must be > 0 and a power of 2");
        }
        if ($N > PHP_INT_MAX / 128 / $r) {
            throw new \InvalidArgumentException("Parameter N is too large");
        }
        if ($r > PHP_INT_MAX / 128 / $p) {
            throw new \InvalidArgumentException("Parameter r is too large");
        }
        return scrypt($password, $salt, $N, $r, $p, $kdlen);
    }
}
